Bridges between separate local area networks (LAN) allow customer premises equipment (CPE) within each LAN to communicate with each other. In accordance with the 802.1q VLAN standard, a Virtual LAN (VLAN) can be set up to allow CPEs in different LANs to communicate as if they were within the same LAN, using transparent bridging. The transparent bridging may be provided by Asynchronous Transfer Mode (ATM) nodes within an ATM network. Each ATM node includes one or more Ethernet cards, each of which is physically connected to an Ethernet switch through a physical port on the Ethernet card or to an Ethernet card on a different ATM node. Each 802.1q Ethernet port allows VLAN configuration. Each VLAN is composed of a plurality of virtual ports, for example one dedicated virtual bridge port and 64 virtual ATM ports.
The ATM node stores a member set, a forbidden set, and an untagged set for each of a number of VLANs, each set containing zero or more virtual ports. The member set and forbidden set of each VLAN are exclusive of each other, in that each virtual port can belong to either the member set or the forbidden set of a given VLAN, but not both. A virtual port can however be associated with more than one VLAN, the set to which it belongs being generally independent for each VLAN. For example, a given virtual port may belong to the member set of a first VLAN, and to a forbidden set of a second VLAN.
When an ATM node receives a VLAN tagged frame from a CPE via an Ethernet switch, the ATM node notes that the frame is VLAN tagged and reads the VLAN identification (ID) of the frame. The ATM determines the virtual ports within the member set associated with the VLAN ID of the received frame, and sends a copy of the frame to each virtual port within the member set. The virtual ports effectively lead to a second LAN within the VLAN, via at least one other ATM node, and arrive at an Ethernet switch within the second LAN. The Ethernet switch then forwards the frame to destination CPEs.
VLANs must be configured at the ATM nodes, in order to identify the member set, forbidden set, and untagged set of each VLAN. VLANs are typically configured manually. An operator telnets into a node and opens a Node Terminal Management Interface session. Using command line interface commands, the operator selects a physical port by entering the shelf, slot, and port number. The operator enters a VLAN ID. The operator selects one of member set, untagged set, or forbidden set and enters the virtual ports to be associated with that set for the VLAN ID. The operator may repeat this for the other two sets. The operator repeats this for each physical port, and for each node in the network.
This manual configuration is a time consuming and tedious process. Furthermore, no error checking is done. As a result, invalid VLAN IDs may be inadvertently used, a VLAN may be inadvertently assigned on a physical port which can not support any additional VLANs, and invalid virtual ports may be inadvertently associated with the VLAN. A configuration method or system which removes the tedium of manual configuration and which performs error checking would allow more efficient and reliable configuration of VLANs on ATM nodes.